Short-circuit-proof heat-exchanger with helical baffles

ABSTRACT

The present invention relates to a short-circuit-proof heat-exchanger with helical baffles, which comprises a housing, helical baffles and heat exchange tubes extending through the helical baffles, wherein two straight sides of the sector baffles with a projection of 360°/4 are respectively widened and overlap in turn, and the heat exchange tubes pass through the overlapping parts. The present invention is characterized in that the short-circuit-proof heat-exchanger with helical baffles also comprises pull rods, wherein one pull rod is positioned on the central axis of the housing and extends through the widened overlapping parts of the helical baffles, and the other pull rods extend through both end areas of the central line of the projection of the widened overlapping parts of the helical baffles; one end of each pull rod is fixed to the internal surface of a tube sheet arranged at one end of the housing, and the other end is fixed to the last corresponding helical baffle; distance tubes are segmentally sheathed on the pull rods. The present invention has the advantages of reasonable structure, increased heat exchange efficiency, enhanced integral rigidity and shockproof performance, simplified assembly technology, saved cost and increased work efficiency. The shell-tube heat exchanger with helical baffles can be extensively used in the technical processes of petroleum industry, chemical industry, power generation industry, metallurgical industry, food industry, pharmaceutical industry, etc.

TECHNICAL FIELD

The present invention relates to a shell-tube heat exchanger with helical baffles for the technical processes of petroleum industry, chemical industry, power generation industry, metallurgical industry, food industry, pharmaceutical industry, etc.

BACKGROUND OF THE INVENTION

Petrochemical devices in China have adopted approximately a thousand shell-tube heat exchangers with helical baffles as shown in FIG. 1. The shell-tube heat exchanger with helical baffles is used to solve the problems of triangle dead zone occupying ⅖ of the heat exchange area, serious dirt deposition, low heat exchange efficiency, short operation period, etc. of vertical bow plate baffling heat exchangers due to large pressure drop of the shell side caused by vertical bow baffling structure. Application results show that compared with the shell side in a vertical bow plate baffling structure, the shell side in a helical baffle structure has the advantage for reducing the fluid pressure drop of the shell side. But actual measurement results show that increase in the heat exchange efficiency of the shell side is not as obvious as anticipated. The heat exchange efficiency of some heat exchangers especially large-diameter heat exchangers in a helical baffling structure is lower than that of heat exchangers in a bow plate baffling structure.

Why is the heat exchange efficiency of heat exchangers with helical baffles lower than that of heat exchangers in a bow plate baffling structure? Many simulation experiments on heat exchangers with housings of different diameters and helical baffles of different angles show that a large number of media form short circuit leakage in triangular space formed between adjacent baffles, which reduces the flow of ideal passages; the larger the diameter of a housing is, the more obvious the phenomenon of short circuit leakage is, and the more the helical flow of a main flow passage decreases, which reduces the flow rate of the media, thereby seriously reducing the heat exchange efficiency. Someone ever suggested adding a triangle blocking plate to the triangular zone, but the plate blocks the flow in the same direction at the back of the baffles, increases the pressure drop and forms a new dead zone, which also results in the problems of the vertical bow baffles.

Short circuit prevention shell-tube heat exchanger with helical baffles as a Chinese patent with the patent number of ZL200620008595.6 discloses an improved shell-tube heat exchanger with helical baffles as shown in FIG. 3. It is characterized in that two straight sides of each sector baffle with a projection of 360°/4 are widened by the distance of one to two rows of tubes, and the widened parts overlap. Simulation results show that through the improvement, the media in the shell side flow through the shell side at ideal helical flow, and the phenomenon of short circuit hardly occurs.

Even so, it can be seen from FIG. 2 that pull rods on the baffles can not be shared, which causes large number of pull rods and unreasonable position and structure. This is mainly indicated by: on one hand, the pull rods occupy too much position of heat exchange tubes, influencing the heat exchange efficiency of the entire device; on the other hand, each baffle is positioned on its curved side by the pull rods while the right-angle zone of the baffle is not positioned by any pull rod, so bad positioning effect influences the integral rigidity and shock proof performance of the heat exchange tubes, thereby shortening the service life of the heat exchange tubes and increasing maintenance cost. Meanwhile, because the overlapping parts of the helical baffles are not integrally penetrated by the same pull rod, and the baffles in two adjacent quadrants can not be connected, the assembly technology of tube bundles appear to be very complex. Usually, the baffles need to be positioned by welding or bound onto the tube bundles by steel wires before assembly, then part of the heat exchange tubes are inserted, and finally the weld zone is cut off, or the steel wires used for binding are removed. Complex process and use of a large number of manpower, material resources and man hours cause increase in manufacturing cost and the probability of errors. Special molds can be used for positioning abroad, which is bound to increase production cost.

SUMMARY OF THE INVENTION

In view of the defects of the prior art, the present invention aims to disclose a short-circuit-proof heat-exchanger with helical baffles, which has a more reasonable structure so that the heat exchange efficiency of the heat exchanger is further increased, the rigidity and the shock proof performance of the equipment are enhanced, the assembly technology of the tube bundles is simplified, the assembly accuracy is increased, the production cost is reduced, the operation efficiency is improved effectively, and the service life of the equipment is prolonged.

The present invention solves the technical problem by adopting the following technical schemes:

A short-circuit-proof heat-exchanger with helical baffles, comprising:

a housing;

helical baffles arranged in the housing;

heat exchange tubes extending through the helical baffles, wherein two straight sides of the sector baffles with a projection of 360°/4 are respectively widened and overlap in turn, and the heat exchange tubes pass through widened overlapping parts; and

pull rods, wherein one pull rod is positioned on the central axis of the housing and extends through the widened overlapping parts of the helical baffles, and the other pull rods extend through both end areas of the central line of the projection of the widened overlapping parts of the helical baffles; wherein one end of each pull rod is fixed to the internal surface of a tube sheet arranged at one end of the housing, and the other end is fixed to the last corresponding helical baffle; distance tubes are segmentally sheathed on the pull rods.

Herein, on one hand, the pull rods extending through the widened overlapping parts of the helical baffles are distributed on two orthogonal planes passing through the central axis of the housing, and occupy the positions of effective heat exchange tubes as little as possible or even do not occupy so that the heat exchange efficiency is increased effectively; on the other hand, the pull rod positioned on the central axis of the housing and the pull rods extending through both ends of the central line of the projection of the widened overlapping parts of the sector helical baffles form the most effective large triangular positioning, thereby enhancing the rigidity and the shock proof performance of the equipment; furthermore, as mentioned above, the pull rod positioned on the central axis extends through all the helical baffles, which is significant for the assembly technology of the tube bundles. By adopting the structure, the assembly technology of the tube bundles is greatly simplified, at least half of manpower and man-hour is saved, and no special assembly mold is used so that assembly cost is greatly saved. Meanwhile, errors caused by welding and binding and damage to the equipment caused by forcedly penetrating tubes are avoided, so assembly accuracy and quality are greatly improved.

The short-circuit-proof heat-exchanger with helical baffles also comprises connecting positioning tubes and pull rods, extending through the intermediate area of the central line of the projection of the widened overlapping parts of the helical baffles; wherein both ends of each connecting positioning tube have a distance away from the tube sheets arranged at both ends of the housing and are fixed to the corresponding baffles arranged at the ends; wherein one end of each pull rod is fixed to the internal surface of the tube sheet arranged at one end of the housing, and the other end is fixed to the last corresponding helical baffle; and distance tubes are segmentally sheathed on the pull rods. Wherein the connecting positioning tubes are hollow metal tubes of which the dimension is the same as that of the external diameter of the heat exchange tubes. Under the condition of large housing diameter, the addition of the pull rods especially the connecting positioning tubes to the position improves the effect of short circuit prevention and enables the position matching of the holes of the heat exchange tubes of the baffles to be accurate. Thereby, the efficiency for penetrating tubes is increased, and the connection between the baffles is consolidated so that the structure of the tube bundles is more compact. Thus, the rigidity and the shock proof performance of the tube bundles are improved, and radial separation at the time of assembly is further avoided.

The widened overlapping parts of the helical baffles have a width of 10 mm to 100 mm. When the housing diameter becomes larger, the widened overlapping parts of the baffles becomes wider so as to prevent short circuit leakage and guarantee the heat exchange efficiency of the shell side.

Compared with the prior art, the present invention has obvious advantages that:

The structure in the technical schemes of the present invention is more reasonable and compact, so the effective heat exchange area is increased, and the phenomenon of short circuit or leakage flow at a triangle dead zone is reduced, thereby increasing the heat exchange efficiency; the integral rigidity and the shock proof and shock resistant performance of the equipment are enhanced, the assembly technology procedures of tube bundles are greatly simplified, the cost is saved, and the work efficiency is increased.

BRIEF DESCRIPTION OF THE FIGURES

The present invention has six figures, wherein

FIG. 1 shows the schematic diagram of the structure of the existing heat exchanger with non-overlapping helical baffles;

FIG. 2 shows the E-E section schematic diagram of FIG. 1;

FIG. 3 shows the schematic diagram of the structure of the existing heat exchanger improved based on FIG. 1;

FIG. 4 shows the F-F section schematic diagram of FIG. 3;

FIG. 5 shows the schematic diagram of the structure of the present invention;

FIG. 6 shows the G-G section schematic diagram of FIG. 5.

In the figures, 1. housing; 2. pull rods; 3. distance tubes; 4. baffles; 5. heat exchange tubes; 6. connecting positioning tubes; 7. tube sheets.

DESCRIPTION OF THE PREFERRED EMBODIMENT Embodiment 1

The housing 1 of the short-circuit-proof heat-exchanger with helical baffles has a diameter of 500 mm and has a length of 3 m, and the heat exchange tubes 5 extend through the helical baffles 4 in the housing. The helical baffles 4 in the housing are in a shape of sector with a projection of 360°/4, two straight sides of the sector baffles 4 are respectively widened by 30 mm and overlap in turn, and the heat exchange tubes 5 extend through the widened overlapping parts. The short-circuit-proof heat-exchanger with helical baffles is also provided with five pull rods 2 with the diameter of 12 mm, wherein one pull rod is positioned on the central axis of the housing and extends through the widened overlapping parts of the helical baffles, and the other four pull rods extend through both end areas of the central line of the projection of the widened overlapping parts of the helical baffles; one end of each pull rod is fixed to the internal surface of the tube sheet 7 arranged at one end of the housing, and the other end is fixed to the last corresponding helical baffle 4; distance tubes 3 are segmentally sheathed on the pull rods 2. The widened overlapping sector helical baffles 4 can guild media flowing through the housing 1, which eliminates the phenomenon of short circuit or leakage flow in the triangular space formed by the crossing of the straight sides of two adjacent sector baffles. The arrangement of the pull rods 2 greatly improves the positioning effect of the baffles 4, and effectively saves the position of the heat exchange tubes 5 occupied by the pull rods in the design of prior art; thus, the heat exchange area is enlarged, and the heat exchange efficiency is improved effectively. Moreover, the pull rod 2 positioned on the central axis extends through all the helical baffles 4, so during the assembly of the tube bundles, firstly, the pull rod 2 on the central axis of the housing is used for successively positioning all the sector baffles 4, and then, tubes are inserted for weaving a cage. Therefore, the whole assembly technology is greatly simplified, at least half of manpower and man-hour is saved, manufacturing cost is saved, and the integral rigidity and the shockproof performance of the equipment are also obviously improved.

Embodiment 2

For the short-circuit-proof heat-exchanger with helical baffles which has the housing 1 with a large diameter for example a diameter greater than Φ1200, two straight sides of the sector baffles 4 are respectively widened and overlap by more than 46 mm, i.e. the width of the widened overlapping parts increases with increase in the diameter of the housing. The arrangement of the pull rods and the heat exchange tubes is the same as that in Embodiment 1. What is different from Embodiment 1 is that the short-circuit-proof heat-exchanger with helical baffles also comprises hollow connecting positioning tubes 6 which have the same external diameter as the heat exchange tubes 5 and have greater diameter than the pull rods 2, wherein the connecting positioning tubes 6 extending through the intermediate area of the central line of the projection of the widened overlapping parts of the helical baffles 4 are distributed between two pull rods 2; both ends of each connecting positioning tube 6 which have a distance away from the tube sheets arranged at both ends of the housing 1 are fixed to the corresponding baffles arranged at the ends of the housing 1, as shown in FIG. 5 and FIG. 6. The addition of the connecting positioning tubes 6 further improves the effect of short circuit prevention, particularly enhances the integral rigidity and the shock proof and shockproof performance of the equipment, and simultaneously enables the position matching of the holes of the baffles and the heat exchange tubes to be accurate, and thus, the efficiency for penetrating tubes is increased. 

1. A short-circuit-proof heat-exchanger with helical baffles, comprising: a housing (1), helical baffles (4) arranged in the housing; heat exchange tubes (5) extending through the helical baffles, wherein two straight sides of the sector baffles (4) with a projection of 360°/4 are respectively widened and overlap in turn, and the heat exchange tubes (5) pass through widened overlapping parts; and pull rods (2), wherein one pull rod is positioned on the central axis of the housing (1) and extends through the widened overlapping parts of the helical baffles (4), and the other pull rods extend through both end areas of the central line of the projection of the widened overlapping parts of the helical baffles; wherein one end of each pull rod (2) is fixed to the internal surface of a tube sheet arranged at one end of the housing (1), and the other end is fixed to the last corresponding helical baffle (4); distance tubes (3) are segmentally sheathed on the pull rods (2).
 2. The short-circuit-proof heat-exchanger with helical baffles of claim 1, also comprising: connecting positioning tubes (6) and pull rods (2), extending through the intermediate area of the central line of the projection of the widened overlapping parts of the helical baffles (4); wherein both ends of each connecting positioning tube (6) have a distance away from the tube sheets arranged at both ends of the housing (1) and are fixed to the corresponding baffles arranged at the ends; wherein one end of each pull rod (2) is fixed to the internal surface of the tube sheet arranged at one end of the housing (1), and the other end is fixed to the last corresponding helical baffle (4); and distance tubes (3) are segmentally sheathed on the pull rods (2).
 3. The short-circuit-proof heat-exchanger with helical baffles of claim 1, wherein the widened overlapping parts of the helical baffles (4) have a width of 10 mm to 100 mm.
 4. The short-circuit-proof heat-exchanger with helical baffles of claim 2, wherein the widened overlapping parts of the helical baffles (4) have a width of 10 mm to 100 mm. 